Film supplying mechanism of a conveying system for a large and light film

ABSTRACT

A conveying system, which is used for conveying a large and light film, includes a film supplying mechanism consisting of a main body, and two cam rollers; the main body has a film inlet, and a film outlet, and all air has to be drawn outside it when the mechanism is used; each cam roller has protruding portions spaced apart and lengthways extending along an outer side, and concave portions between the protruding portions; the cam rollers are positioned side by side near the film outlet, and define a conjugate curve between them; the cam rollers can touch each other closely to prevent air from traveling into the main body while rotating to move a film along that is sandwiched between them, thus preventing negative pressure of the main body from disappearing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a film supplying mechanism of a conveying system for a large and light film, more particularly one, which are equipped with two cam roller members used for moving a film along; the cam roller members are made and shaped in such a way that they can remain in good condition after having been used for a long period of time, thus capable of effectively preventing air from traveling into the supplying mechanism, in which negative pressure has to be maintained.

2. Brief Description of the Prior Art

Referring to FIGS. 3 and 4, a conventional film supplying mechanism 4 of a conveying system for a large and light film, e.g. plastic film, includes a main body 41, and two rollers 42 and 43. The main body 41 has a film inlet 411 at an upper end, a film outlet 412 at a lower end thereof. The rollers 42 and 43 are arranged side by side near the film outlet 412 in the main body 41, and they have flexible blades 421, 431 spaced apart on and lengthways extending along outer sides thereof. The flexible blades 421 will touch the main body of the roller 43 closely at outward ends thereof, and the flexible blades 431 will touch the main body of the roller 42 closely at outward ends thereof while the rollers 42 and 43 are rotating.

To use the conveying system, all air is drawn outside the main body 41 of the supplying mechanism 4, and the rollers 42 and 43 are made to rotate. Thus, negative pressure is formed in the main body 41, and a film will pass into the main body 41 via the inlet 411, and pass into between the rollers 42 and 43. And, the film will be moved outside the main body 41 via the outlet 412 by the rollers 42 and 43.

Because the flexible blades 421 and 431 have such shape, they are prone to lose elasticity and change shape after certain period of time of use, incapable of preventing air from traveling into the main body 41 of the supplying mechanism 4. Therefore, negative pressure of the main body 41 can't be maintained, and the downward drawing force on the film will disappear. Consequently, the film will fly upwards, and prone to cause blockage to the supplying mechanism. From the above, it can be seen that the above conventional film supplying mechanism needs frequent maintenance, and isn't economical or convenient to use.

SUMMARY OF THE INVENTION

It is a main object of the present invention to provide an improvement on a film supplying mechanism of a conveying system for a large and light film to overcome the above disadvantages.

The film supplying mechanism includes a main body, and two cam rollers, which can't lose elasticity or change shape. The main body has a film inlet, and a film outlet, and all air has to be drawn outside it when the mechanism is used. Each roller has protruding portions spaced apart and lengthways extending along an outer side, and concave portions between the protruding portions. The cam rollers are positioned side by side near the film outlet, and define a conjugate curve between them; the cam rollers can touch each other closely to prevent air from traveling into the main body through between them while rotating to move a film through the supplying mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood by referring to the accompanying drawings, wherein:

FIG. 1 is a vertical section of the film supplying mechanism of a film conveying system according to the present invention,

FIG. 2 is a partial vertical section of the present film supplying mechanism,

FIG. 3 is a vertical section of the conventional film supplying mechanism of a film conveying system, and

FIG. 4 is a partial vertical section of the conventional mechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, a preferred embodiment of a film supplying mechanism of a conveying system for a large and light film includes a main body 1, and two cam rollers 2 and 3.

The main body 1 has a film inlet 11 at an upper end, a film outlet 12 at a lower end thereof. The cam rollers 2, 3 have several protruding portions 21, 31 spaced apart and lengthways extending along outer sides thereof, and concave portions between the protruding portions 21, 31. The cam rollers 2, 3 are arranged side by side near the film outlet 12 in the main body 1. While the cam rollers 2 and 3 are rotating in opposite directions, the protruding portions 21 will touch the concave portions of the cam roller 3 closely, and the protruding portions 31 will touch the concave portions of the cam roller 2 closely, and the rollers 2 and 3 define a conjugate curve between them. Thus, when the cam rollers 2 and 3 rotate, air can't travel into the main body 1 through between them.

To use the conveying system, all air is drawn outside the main body 1 of the supplying mechanism, and the rollers 2 and 3 are made to rotate in opposite directions (clockwise and counterclockwise respectively). Thus, negative pressure is formed in the main body 1, and a film will pass into the main body 1 via the inlet 11, and pass into between the cam rollers 2 and 3. And, the film will be moved outside the main body 1 via the outlet 12 by the cam rollers 2 and 3; because the cam rollers 2 and 3 can prevent air from traveling into the main body 1, negative pressure of the main body 1 won't disappear.

Because the cam rollers 2, 3 are formed with the protruding portions 21, 31 and the concave portions as the means for making the main body 1 of the film supplying mechanism airtight, which can't lose elasticity or change shape. Therefore, the film supplying mechanism of the present invention doesn't have the disadvantages of the conventional one. 

1. A film supplying mechanism of a conveying system for a large and light film, comprising a main body having a film inlet at an upper end, and a film outlet at a lower end; and first and second cam rollers positioned side by side near the film outlet in the main body for moving a film along that passes between them; each of the cam rollers having a plurality of protruding portions lengthways extending along an outer side thereof; each cam roller having concave portions between the protruding portions thereof; the cam rollers being capable of touching each other closely to prevent air from traveling into the main body while rotating to move a film along; the cam rollers defining a conjugate curve between them. 